1. Field of the Invention:
The present invention relates to control systems for nuclear steam power plants utilizing once through steam generators and, more particularly, to such control systems having independent control subsystems for reactor, feedwater and turbine steam demand control.
2. Background of the Invention:
Nuclear steam power plants utilizing once through steam generators for generating electrical power from nuclear energy conventionally utilize an integrated system of automatic controls for the reactor, the feedwater flow to the steam generator(s), and the turbine steam demand. Such integrated control systems operate effectively when properly aligned or "tuned" and when all components are functioning properly; however, when the systems become misaligned or a component fails, complicated transients, where more than one plant boundary condition responds spuriously, are generated which are difficult to control due to the complexity of the integrated control systems and the interaction of the various controls based on shared control system parameters. Other disadvantages of prior art integrated control systems for nuclear steam power plants are that, due to the complexity of such systems, plant operators are not able to fully understand the operation and, therefore, when failures occur such systems are shut down in favor of manual control, that additional manpower is accordingly required, and that it is difficult to determine the origin of system upsets leading to unnecessary confusion and system shut down.
The Babcock and Wilcox Integrated Control System, as described in a paper presented to the American Nuclear Society Annual Meeting, Toronto, Canada, June 13-18, 1976 entitled "Dynamic Behavior of the B&W Nuclear Steam System" and as implemented at the Davis-Besse Nuclear Power Station, is representative of prior art nuclear steam power plant control systems wherein subsystems for reactor,, steam generator/feedwater, turbine and turbine bypass controls, are interconnected to produce an integrated control for the plant, with control of each subsystem established from a central or integrated master.